Verdict
Built from the measurements below
- Accuracy is too close to call: Gemini 4 Argon scored 84.8% and GPT-5.3-Codex 82.5% on the same 79 questions, a gap within what chance alone could produce.
- Gemini 4 Argon is 1.6× cheaper per question as billed ($0.0063 vs $0.01), reasoning tokens included.
- GPT-5.3-Codex generates text 1.4× faster: 95 tokens per second against 69.
- GPT-5.3-Codex starts answering sooner: 1.4 s to the first token, against 3.3 s for Gemini 4 Argon.
- Gemini 4 Argon accepts more context: 1M tokens against 400k.
Which should you choose?
Choose Gemini 4 Argon for the lower cost per correct answer ($0.0074 against $0.013) and a 1M-token context window. Choose GPT-5.3-Codex for faster streaming and a quicker first token. The widest subject gap is in law: Gemini 4 Argon answered 6 of 6 correctly, GPT-5.3-Codex 4 of 6. With so few questions per subject, treat this as a lead to test on your own prompts, not a result.
Accuracy gap +2.3 points (z = 0.39). We call a winner only when z is at least 1.96, the usual 95% threshold. Speed, latency and price need a 10% margin.